a) Field of the Invention
The present invention relates to a magnetic card reader and a method for determining the coercive force of a magnetic card therein. More specifically, it relates to a magnetic card reader, which has a function to automatically determines whether the coercive force of a magnetic card is high or low, and a method for determining the coercive force of a magnetic card therein.
b) Description of the Related Art
In a conventional magnetic card reader, magnetic cards having identical coercive force are used. In other words, the coercive force of magnetic cards used therein is designated in advance; therefore, such a magnetic card reader is not capable of handling magnetic cards with more than two different levels of the coercive force.
Also, the coercive force is defined as a force of a magnetic field required to reverse the direction of a magnetic flux, and its unit is indicated by Oe (oersted) or A/m (ampere per meter).
In recent years, it is reported that data on a magnetic card, such as a credit card, are erased due to the effects of magnets used for clasps of purses or magnets used for driving a motor in a mechanism of a portable phone to notify receiving of a message by vibration. Therefore, it is a current tendency that the coercive force of magnetic cards be increased. For example, low coercive force cards at 300 (Oe) are tended to be altered to high coercive force cards at 2,750 (Oe). As a result, there is a possibility that both low coercive force cards and high coercive force cards may be used with the same card reader during a transition period.
In general, in the case of writing data on magnetic cards with different coercive forces, appropriate card output cannot be obtained unless appropriate writing current corresponds to the coercive force. Therefore, it is necessary to equip a magnetic card reader with a function for determining whether a magnetic card inserted from a card insertion slot is a high coercive force card or low coercive force card to establish appropriate writing current corresponding to the coercive force of the magnetic card.